Question

代码

def substring(word,f,l):
    word_length = len(word)
    l1 = str(word.index(f))
    l2 = str(word.index(l))
    a = word[int(l1):int(l2)+1]
    sub_list = []
    for i in l1:
        for j in l2:
            sub_list.append(a)
    return sub_list

w1 = input("Enter String: ")
w2 = input("Enter start: ")
w3 = input("Enter end: ")
print(substring(w1,w2,w3))

输入

python programming # string
p                  # start
g                  # end

输出

['python prog', 'python prog']

预期产量

['python prog', 'prog', 'programming']

我该怎么做才能根据用户输入获取字符串中的所有子字符串？

Answer 1

您可以使用正则表达式查找字符串中所有出现的开始和结束符号，并使用列表推导构造答案：

s = input("Enter String: ")
head = input("Enter start: ")
tail = input("Enter end: ")

result = [s[i.start():j.start() + 1] 
          for i in re.finditer(head, s) for j in re.finditer(tail, s)
          if i.start() < j.start()]

print(result)

输出

['python prog', 'prog', 'programming', 'python programming']

Answer 2

def substring(line, start, end):
    for i in (start, end):
        if i not in line:
            raise Exception(f"`{i}` not found in `{line}`!")
    start_indexes, end_indexes, sub_list = [], [], []
    line_length, end_length = len(line), len(end)
    for i in range(len(line)):
        if line[i:].startswith(start):
            start_indexes.append(i)
        elif line[i:].startswith(end):
            end_indexes.append(i)
    for i in start_indexes:
        for j in end_indexes:
            right = j + end_length
            if i < right and right-i < line_length:
                sub_list.append(line[i : right])
    return sub_list

输出：

['python prog', 'prog', 'programming']

Answer 3

.index()仅给出第一个索引（而.rindex()给出最后的索引），您需要所有索引，所以enumerate这样做：

def substring(word,f,l):
    word_length = len(word)
    l1 = [i for i,v in enumerate(word) if v==f]
    l2 = [i for i,v in enumerate(word) if v==l]
    sub_list = []
    for i in l1:
        for j in l2:
            sub_list.append(word[i:j+1])
    return sub_list

w1 = input("Enter String: ")
w2 = input("Enter start: ")
w3 = input("Enter end: ")
print(substring(w1,w2,w3))

输出：

Enter String: python programming
Enter start: p
Enter end: g
['python prog', 'python programming', 'prog', 'programming']

Answer 4

使用re模块（explanation of regexp here）的另一尝试：

import re
from itertools import chain

string = 'python programming' # string
start = 'p'                   # start
end = 'g'                     # end

groups = re.finditer(rf'(?=({start}.*{end}))(?=({start}.*?{end}))', string)
s = set(chain.from_iterable([(g.start(1), g.end(1), g[1]), (g.start(2), g.end(2), g[2])] for g in groups))
print([i[2] for i in s])

打印：

['prog', 'python prog', 'programming', 'python programming']

如何获取字符串中的所有子字符串（用户输入）

4 个答案: